Independently and not as an agent of the United States Government, the Kaiser Foundation Research Institute shall conduct population-based case- control studies of oral contraceptives and the risk of acute myocardial infarction (AMI and stroke). Accordingly, hospitalized AMI and stroke cases arising in the membership of the Kaiser Permanente Medical Care Programs in Northern California and Southern California shall be identified as potential study recruits. In the conduct of these investigations, Kaiser shall identify and collect diagnostic, contraceptive use, and cardiovascular risk factor data on approximately incident cases of acute myocardial infarction (AMI) and 320 cases of stroke. Approximately 1500 controls shall be incorporated as part of the interviewing data processing, and analysis efforts of this contract. The contract shall be conducted in five phases including: (1) a start up phase; (2) a case ascertainment and data collection phase, and (3) through (5) various extensive data analysis phases.